The present disclosure generally relates to depth sensing, and specifically relates to a camera assembly with a programmable diffractive optical element (PDOE) for three-dimensional depth sensing.
To achieve a compelling user experience for depth sensing when using head-mounted displays (HMDs), it is important to create a scanning device that provides illumination pattern that is dynamically adjustable in real time. Most depth sensing methods rely on active illumination and detection. The conventional methods for depth sensing involve mechanical scanning or fixed diffractive-optics pattern projection, using structured light or time-of-flight techniques. Depth sensing based on time-of-flight uses a mechanical based mirror device (scanner) to send short pulses into an object space. The depth sensing based on time-of-flight further uses a high speed detector to time-gate back-scattered light from the object to create high resolution depth maps. However, the mechanical based scanner performs inadequately in scanning speed, real-time reconfiguration and mechanical stability. Depth sensing based on a fixed structured light uses a diffractive optical element to generate a structured light of a static (fixed) pattern projected into an object space. The depth sensing based on the fixed structured light further uses a pre-stored look-up table to compute and extract depth maps. However, the depth sensing based on the fixed structured light and the diffractive optical element is not robust enough for dynamic depth sensing where adjustment in illumination pattern is required.